Locking mechanism for egg cartons



United States Patent [72] Inventor Robert B. Gaylon-,Jr. [56] References Cited Pittsburgh, Pennsylvania UNITED STATES PATENTS '1 PP 820,580 2,217,455 10 1940 Price et a] 229/44x 1 FM 1969 2,771,253 11/1956 Cox 229/29x I 1 Pwmed oft-27,1970 3,258,187 6/1966 Greatman. 229/25 1 Asslgnee Sinclair-K01)? 3.285.491 11/1966 Bessett 1. 229/45x g 3,458,108 7/1969 Howarth et al. 229/45x a partnership of Delaware Primary Examiner-Davis T. Moorhead Attorneys Finnegan, Henderson and Farabow and Olin E.

Williams ABSTRACT: A locking mechanism for an egg carton having an integrally hinged tray and cover. The locking mechanism [54] LOCKlNG MECHANIM FOR EGG CARTONS includes a locking flap hingedly connected to the front of the Claims Drawing cover and locking detents extending inwardly from the flap [52] U.S. Cl 229/44, that engage the underside of a protruding lip on the cartons 229/25, 229/45 tray when the canon is closed. Lugs are provided on the top of [51] int. Cl B6511 5/66 the tray that extend through the cover and pivot the locking [50] Field of Search 229/25. flap into locking engagement as the tray and cover are moved 29( M), 44. 45 into closed position.

Patented Oct .27, 1970 3,536,250

Sheet 1 of 3 RO BERT B. GAYLOR, JR.

jzllegan, J /enamon Qflaow ATTORNEYS Patented Oct. 27, 1970 3,536,250

Sheet 2 of 3 FIG. 2

FIG. 3

INVENTOR ROBERT B. GAYLOR, JR.

32/263012, fen darson Qlzlafioa;

Patented Oct. 27, 1970 A 3,536,256

Sheet 5 0:3

. INVENTOR ROBERT B. GAYLOR,JR.

Enyan, J- wza uzson (935M614) ATTORNEY LOQKING MECHANISM FOR EGG CARTONS SPECIFICATION This invention relates to packaging cartons, and more particularly to a new and improved locking mechanism for molded egg cartons.

Molded with various types of integrally molded locking mechanisms have been provided in the past for the packaging of eggs. Exemplary of one widely used type of mechanism provides a pair of lugs protruding outwardly from a flap hingedly connected to the front of the cartons tray and matable apen .tures in the front wall of the cartons lid through which the lugs extend to lock the lid to the tray.

Cartons utilizing this type of locking mechanism, however, have generally proven unsatisfactory to housewives and other users because they are difficult to open and close. The luglocking feature, for example, requires flexing of the cartons walls, and due to the inherent stiffness of thematerial used in the manufacture of such cartons and the outward pressure of the packaged articles, it is difficult for the user to flex the structure sufficiently to allow for easy opening and closing. During closing, for example, the front wall of the lid must be pulled outward to insert the lugs through the openings and during opening the front wall of the tray must be pushed inwardly to free the lugs from the openings. Such difficulties, of course, are not only inconvenient to the user, but render the carton and the packaged articles prone to being damaged during repeated opening and closing of the carton.

In accordance with the present invention, a new and improved locking mechanism for packaging cartons is provided in which the carton includes a bottom section having a front wall with a protruding lip and a rear wall; and a cover section having a front wall and a rear wall, the cover and bottom sections rear walls being hingedly connected so that the cover section can assume a closed-superimposed position with the respect to the bottom section.

Interlocking means are provided on the front walls of the cover and bottom sections for releasably holding the carton closed, in which the interlocking means includes a locking flap hingedly connected to the cover sections front wall and at least one locking detent protruding inwardly from the flap, the locking detent engaging the underside of the protruding lip of the bottom sections front wall when the carton is closed to lock the sections together.

The interlocking means further includes cam means for pivoting and holding the locking flap in locking position as the sections are moved into closed position, in which the cam means comprises at least one lug protruding upwardly from the top of the bottom sections front wall, and an aperture in the cover sections front wall through which the lug extends as the sections are moved into closed position, a said locking flap being engaged by the lug as it passes through the aperture to pivot the locking flap down and its attached locking detent into locking engagement with the underside of the bottom sections protruding lip.

Preferably, the packaging carton is an egg carton and the carton and interlocking means are of unitary molded construction.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory but are not restrictive of the invention.

The accompanying drawings which are incorporated in and constitute a part of a specification illustrate an embodiment of the invention, and together with the description serve to explain the principles of the invention.

Of the drawings:

FIG. I is a plan view of an open egg carton showing the locking mechanism of this invention;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a fragmentary perspective view of the front of the carton of FIG. 1 in a closed position;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4; and

FIG. 6 is a sectional view similar to FIG. 5 but modified to show the carton in a slightly open position.

Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings.

The packaging carton illustrated in the drawings and contemplated for use with the lockingmechanism of this invention is an egg carton having a cover section or lid 10 and a bottom section or tray 12. The cover and bottom sections rear walls 14 and 16, respectively, are hingedly connected by an integral web 18. Bottom section l2 has a plurality of egg accomodating cells 20 arranged in parallel rows. While the number and rows of cells may vary, the bottom section preferably consists of a dozen cells arranged in two (2) parallel rows of six (6) cells each.

A wide variety of materials may be used in the manufacture of the carton structure illustrated in the drawings. Molded paper pulp, pasteboard, plastic and the like, for example, may be used. A preferred material, however, is thermoplastic foam, such as, for example, foam polystyrene, or other polymers, such as polyethylene, polypropylene, polyvinylchloride, and the like. For purposes of illustration, and as a preferred embodiment, the drawings show an egg carton and locking mechanism for the carton of unitary construction produced by vacuum molding or matchmolding techniques from the sheet of polystyrene foam.

In accordance with the invention, interlocking means are provided on the front walls of the cover and bottom sections for releasably holding the carton closed. The relationship between the interlocking means and the top and bottom sections of the carton as shown in the drawings will be used for clarity in the specification and claims, but it is to be understood that the various parts of the interlocking means may be reversed with respect to the cartons sections without departing from the scope of this invention.

As embodied, the interlocking means includes a locking flap 22 hingedly connected at 24 to the bottom of the front wall 26 of cover section 10 so that the flap, when the cartons sections are in closed position as shown in FIG. 4, will be located in front of the front wall 28 of bottom section 12. Locking flap 22 has a plurality of locking detents 30, three (3) being shown in the drawings, that protrude inwardly from the flap, with each detent having an upper locking edge 32.

In closed position, the locking edges 32 on each locking detent 30 engage the underside ofa protruding lip 34 on the top of bottom sections front wall 28 to lock the sections together.

The interlocking means further includes cam means for pivoting locking flap into 22 into locking position as the cover and the bottoms sections are moved into closed position. As embodied, the cam means comprises a plurality of lugs 36, two (2) of which are shown. in the drawings that protrude upwardly from lip 34 on the bottom sections front wall. 28. As best shown in FIG. 2, the front surface 37 of lugs 36 slants upwardly and outwardly so that its top edge 39 is slightly forward of the front edge 35 of the bottom sections protruding lip 34. Preferably, and as best shown in FIG. 1, lugs 36 are located between adjacent pairsof locking detents 30.

Matable with lugs 36 are a plurality of apertures 38 in the bottom of the cover sections front wall 26. Lugs 36 and apertures 38 are located on the front walls of their respective sections so that the lugs extend through the apertures without interference and without flexure of either wall when the sections are moved into closed position.

As best shown in FIG. 4, the cover sections front wall 26 has plurality of pairs of angularly offset vertical walls 40, the walls of each pair intersecting one another to form a channel 42 that extends vertically up from apertures 38. The purpose of channels 42 will be more fully described below.

The cam means also includes a plurality of cam projections 44 located adjacent each channel 42. Projections 44 are integral with and extend upwardly from the top of locking flap 22 and have a height slightly less than the depth of the base of channels 42.

As best shown in FIG. 6, and when the sections of the egg carton are moved into closed position, the plurality of lugs 36 on bottom sections front wall 28 pass upwardly through corresponding apertures 38 in cover section's front wall 26 and the top edges 39 of lugs 36 push against the inner surface 46 of cam projections 44. Lugs 36 acting against projections 44 thus pivot locking flap 22 down about hinge 24 to automatically engage the locking edges 32 of locking detents 30 with the underside of protruding lip 34 on the bottom sections front wall 28 (see FIG. 4). After closure, the slanted surfaces 37 of lugs 36 hold locking flap 22 in locked position.

For convenience in molding the egg carton and its attached locking mechanism, and with reference to HO. 1, cam projections 44 are most advantageously formed by simply cutting or stamping out a half moon cut 48 on the bottom of channels 42 on the cover sections front wall 26. Such a cut simultaneously forms projections 44 on locking flap 22 and corresponding apertures 38 at the bottom of channels 42.

To strengthen the interlocking means during use, lugs 36 are located on the top of carton ribs 50 that form the egg accommodating cells 20, and ribs 51 are molded integral with locking flap 22 to strengthen projections 44.

Lugs 36 and corresponding projections 44 on locking flap 22 further assist in the unlocking and separation of the bottom and cover sections of the carton. During unlocking and opening, and as best shown in H6. 6, locking flap 22 is pulled outwardly and upwardly and about hinge 24, by inserting the fingers between the flap and the bottom section's front wall 28, pulling locking detents 30 out of engagement with the underside of protruding lip 34. During upward movement of locking flap 22, the inner surfaces 46 of projections 44 act against the top edges 39 of lugs 36, tending to separate the cover from the bottom section. Channels 42 in cover sections front wall 26 permit projections 44 to pivot inwardly and downwardly about hinge 24 and against lugs 36 until they reach a position essentially closing apertures 38 when the locking flap is substantially co-planar with the bottom of cover section (i.e., as shown in FIG. 2).

The integral web 18 connecting the rear walls 14 and 16 of the cover and bottom sections, respectively, is preferably doubly creased at 52 and 54 to provide a double-hinge with a compressible midportion 56 that resiliently urges the cover and bottom sections apart. Thus, locking detents 30 snap tightly into engagement with the underside of the bottom sections protruding lip 34 when the carton is closed.

It will be understood that while the preferred construction for the locking mechanism has been described, theillustrated shape of locking detents 30, lugs 36, or projections 44, for example, may be varied. For example, cut 48 can be rectangular or even V-shaped, instead of the U-shaped cut shown in the drawings. Further, a single locking detent may extend substantially all along the inner surface of locking flap 22. Other variations within the scope of the invention will, of course, be apparent to those skilled in the art.

lt is to be further understood that the carton described in the drawings and utilizing the locking mechanism of this invention is a preferred carton design for eggs. The invention, however, is applicable to a variety of egg carton shapes and other similar cartons. An egg carton, for example, have three (3) parallel rows of four (4) egg accommodating cells each could readily be used with the present locking mechanism.

The invention thus provides a new and improved locking mechanism for packaging cartons, and particularly molded egg cartons. The locking mechanism facilitates the easy closing with automatic and positive locking, and the easy opening of the carton without the need for applying excessive pressure to the carton, and without fear of damage to the carton or to its contents. Further, the locking mechanism of this invention can be integrally molded with the egg carton from a sheet of suitable material using conventional molding techniques.

The invention in its broader aspects is not limited to the specific details shown and described, and departures may be made from such details without departing from the principles of the invention and without sacrificing its chief advantages.

l claim: I 1. A packaging carton comprising a bottom section having a front wall with a protruding lip and a rear wall; a cover section having a front wall and a rear wall, the cover and bottom sections rear walls being hingedly connected so that the cover section can assume a closed-superimposed position with respect to the bottom section; and interlocking means on the front walls of the cover and bottom sections for releasably holding the carton closed, said inner interlocking means comprising:

a. a locking flap hingedly connected to the cover section's front wall;

b. at least one locking detent protruding inwardly from the flap, the locking detent engaging the underside of the protruding lip of the bottom sections front wall when the carton is closed to hold the sections together; and

c. cam means for pivoting and holding the locking flap in locking position as the sections are moved into closed position, said cam means comprising:

i. at least one lug protruding upwardly from the top of the bottom section's front wall, and

ii. an aperture in the cover sections front wall through which the lug extends as the sections are moved into closed position; said locking flap being engaged by the lug as it passes through the aperture to pivot the locking flap down and its attached locking detent into locking engagement with the underside of the bottom sections protruding lip.

2. The carton of claim 1, in the form of an egg carton with the bottom section having a plurality of egg accommodating cells.

3. The carton of claim 1, wherein the carton is of unitary molded construction.

4. The carton of claim 3, wherein the molded carton is formed of foamed polystyrene.

5. The carton of claim 1, including a plurality of locking detents protruding inwardly from the locking flap.

6. The carton of claim 1, including a plurality of lugs protruding upwardly from the top of the bottom sections front wall, and a plurality of corresponding apertures in the cover sections front wall.

7. the carton of claim 6, wherein the locking flap is hingedly connected substantially along one side to a protruding lip on the cover sections front wall, and a plurality of projections, integral with the locking flap, extends in a direction opposite of the flap from the hinged connection, said projections being engaged by the lugs as the lugs pass through the apertures to urge the locking flap down into locking position.

8. The carton of claim 7, in which the faces of the lugs adjacent the projections on the locking flap slant upwardly and outwardly.

9. The carton of claim 7, wherein the front wall of the carton includes a plurality of sets of angularly offset vertical walls that intersect one another to form a plurality of inwardly extending channels, said channels being open at the bottom to form the apertures in the cover sections front wall and permitting the projections to partially close the apertures when the locking flap is substantially coplanar with the bottom of the cover sections front wall.

10. The carton of claim 7, in which the projections act against the lugs to separate the cover and bottom sections as the locking flap is pulled out of locking position.

11. The carton of claim 1, wherein the locking detent and the underside of the protruding lip of the bottom sections front wall are tightly engaged.

12. The carton of claim 11, wherein the hinged connection between the cover and bottom sections rear walls resiliently urges the sections apart so that the locking detents snap into tight engagement with the underside of the protruding lip of the bottom sections front wall when the sections are moved into closed position. 

